Heat exchanger with recuperating and condensing functions and heat cycle system and method using the same

ABSTRACT

A heat exchanger with recuperating and condensing functions is provided. The heat exchanger includes a pressure vessel, a recuperating pipe and a cooling stream pipe. The pressure vessel has an inlet, an outlet and a baffle. The baffle, located between the inlet and the outlet, divides the interior of the pressure vessel into a working fluid recuperating region and a working fluid condensing region. The recuperating pipe is disposed in the pressure vessel, and passes through the working fluid recuperating region to heat a liquid working fluid flowing through the recuperating pipe. The cooling stream pipe is disposed in the pressure vessel, and passes through the working fluid condensing region to cool a vapor working fluid flowing into the pressure vessel. The vapor working fluid passes through the working fluid recuperating region and then flows into the working fluid condensing region.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefits of U.S. provisional application Ser. No. 61/867,196, filed Oct. 19, 2013 and Taiwan application Serial No. 102142445, filed Nov. 21, 2013, the disclosures of which are incorporated by references herein in its entirety.

TECHNICAL FIELD

The technical field relates to heat exchanger with recuperating and condensing functions, a heat cycling system and a heat exchanging method.

BACKGROUND

Power generation market using middle and low grade waste heat has gained rapid growth in recent years. Of the currently available power generation technologies using middle and low grade waste heat, organic rankine cycle (ORC) technology is most matured and cost-effective. ORC is a closed heat engine cycling system, and its key components and principles of operation thereof are as follows: (1) A working fluid booster pump: boosting a liquid working fluid and feeding the liquid working fluid into an evaporator to be heated therein. (2) An evaporator: absorbing the thermal energy from the heat source to vaporize the working fluid. (3) An expander/a turbine and a power generator: converting the thermal energy and pressure energy of the working fluid into shaft power of the expander for the power generator to generate power. (4) A condenser: condensing a vapor working fluid after work-done into a liquid working fluid and sending the liquid working fluid to an inlet of the working fluid booster pump to complete the heat engine cycle.

A working fluid inside an ORC loop is boosted by a pump, evaporated by an evaporator, work-done by an expander, and liquefied by a condenser so as to complete a closed heat engine cycle. The thermal energy of the hot stream from the heat source is transferred to the working fluid through the evaporator. Inside the evaporator, the thermal energy of the hot stream is absorbed by a heat transfer medium (such as a heat transfer pipe of a shell and tube type heat exchanger or a heat transfer plate of a plate type heat exchanger). The hot stream, having been dissipated by the evaporator, flows to an external environment through a hot stream outlet of the evaporator. The hot stream can be directly discharged or reused depending on the temperature and flow rate of the hot stream in the outlet.

However, if the temperature of the vapor working fluid, having done work, is too high, more heat capacity of the condenser will be needed. On the other hand, if the temperature of the liquid working fluid whose pressure has been booted is too low, more heat capacity of the evaporator will be needed. Consequently, thermal efficiency cannot be effectively increased.

SUMMARY

The disclosure is directed to a heat exchanger with recuperating and condensing functions and a heat cycling system achieving superior thermal energy utilization and recovery efficiency and capable of reducing the requirement of the heat capacity of the heat exchanger.

The disclosure is directed to a heat exchanging method achieving superior thermal energy utilization and recovery efficiency and capable of reducing the requirement of the heat capacity of the heat exchanger.

According to one embodiment, a heat exchanger with recuperating and condensing functions is provided. The heat exchanger comprises a pressure vessel, a recuperating pipe and a cooling stream pipe. The pressure vessel has an inlet, an outlet and a baffle. The baffle, located between the inlet and the outlet, divides the interior of the pressure vessel into a working fluid recuperating region and a working fluid condensing region. The recuperating pipe is disposed in the pressure vessel, and passes through the working fluid recuperating region to heat a liquid working fluid flowing through the recuperating pipe. The cooling stream pipe is disposed in the pressure vessel, and passes through the working fluid condensing region to cool a vapor working fluid flowing into the pressure vessel. The vapor working fluid passes through the working fluid recuperating region and then flows into the working fluid condensing region.

According to another embodiment, a heat cycling system is provided. The heat cycling system comprises a heat exchanger with recuperating and condensing functions, an evaporator, a power generation module and a pump. The heat exchanger with recuperating and condensing functions comprises a pressure vessel, a recuperating pipe and a cooling stream pipe. The pressure vessel has an inlet, an outlet and a baffle. The baffle, located between the inlet and the outlet, divides the interior of the pressure vessel into a working fluid recuperating region and a working fluid condensing region. The recuperating pipe is disposed in the pressure vessel, and passes through the working fluid recuperating region to heat a liquid working fluid flowing through the recuperating pipe. The cooling stream pipe is disposed in the pressure vessel, and passes through the working fluid condensing region to cool a vapor working fluid flowing into the pressure vessel. The vapor working fluid passes through the working fluid recuperating region and then flows into the working fluid condensing region. The evaporator is connected to an outlet of the recuperating pipe to heat the liquid working fluid up to a vapor state. The power generation module is connected to an outlet of the evaporator through a first pipe and is connected to the inlet of the pressure vessel through a second pipe. The pump is connected to the outlet of the pressure vessel through a third pipe, and is connected to an inlet of the recuperating pipe through a fourth pipe.

According to another embodiment, a heat exchanging method is provided. A pressure vessel having a recuperating pipe, a cooling stream pipe and a baffle is provided. The baffle divides an interior of the pressure vessel into a working fluid recuperating region and a working fluid condensing region, the recuperating pipe passes through the working fluid recuperating region, and the cooling stream pipe passes through the working fluid condensing region. A vapor working fluid is introduced into the pressure vessel to heat a liquid working fluid flowing through the recuperating pipe. The vapor working fluid is guided to flow into the working fluid condensing region from the working fluid recuperating region. The vapor working fluid is guided to pass through the working fluid condensing region to cool the vapor working fluid to a liquid state.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is a heat exchanger with recuperating and condensing functions according to an embodiment.

FIG. 2 is a heat cycling system according to an embodiment.

FIG. 3 is a flowchart of a heat exchanging method according to an embodiment.

FIGS. 4A and 4B are schematic diagrams of deflectors being a perforated plate and a spiral deflector respectively.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

In an exemplary example of this embodiment, a heat exchanger with recuperating and condensing functions is used to heat the liquid working fluid at a high pressure side and at the same time cool the vapor working fluid at a low pressure side. For instance, before a liquid working fluid, has been pressure-boosted by a pump, flows into the evaporator, the liquid working fluid flows into a recuperating pipe to absorb the thermal energy so that the temperature of the sub-cooled liquid working fluid is increased and the requirement of the heat capacity (or heat transfer area) of the evaporator is reduced. In addition, before the low pressure vapor working fluid, after work-done, is condensed, the low pressure vapor working fluid releases partial thermal energy to lower the temperature of the vapor working fluid so that the requirement of the heat capacity (or heat transfer area) of the condenser is reduced. By doing so, the requirements of the heat capacity of the evaporator and the condenser can be reduced at the same time.

In an embodiment, the heat exchanger has recuperating and condensing functions, and requires one pressure vessel. If the recuperator and the condenser are separately disposed, apart from the installation cost, additional certification cost for pressure vessel would incur because the recuperator belongs to one type of pressure vessel.

In an embodiment, the pressure vessel has a baffle, which divides the interior of the pressure vessel into a working fluid recuperating region and a working fluid condensing region. The vapor working fluid transfers the thermal energy to the sub-cooled liquid working fluid in the working fluid recuperating region whose function is like a recuperator. Then, the vapor working fluid transfers the thermal energy to an external cooling stream in the working fluid condensing region whose function is like a condenser. Since the heat transfer of recuperated working fluid and the heat transfer of condensed working fluid are both performed in the pressure vessel and are divided by a baffle, both the required pipe length for exchanging the heat and the installation cost of the heat exchanger are reduced.

Referring to FIG. 1, a heat exchanger with recuperating and condensing functions according to an embodiment is shown. The heat exchanger 101 comprises a pressure vessel 110, a recuperating pipe 120 and a cooling stream pipe 130. The pressure vessel 110 has an inlet 111, an outlet 112 and a baffle 113. The baffle 113, located between the inlet 111 and the outlet 112, divides the interior of the pressure vessel 110 into a working fluid recuperating region 110 a and a working fluid condensing region 110 b. In this embodiment, the baffle 113 is disposed for providing the heat exchanger 101 with recuperating and condensing functions. Since only one pressure vessel 110 is required, the installation cost of the heat exchanger 101 can thus be reduced.

In an embodiment, the pressure vessel 110 has a first terminal plate 114 and a second terminal plate 115. The two terminal plates are connected to an inner wall of the pressure vessel 110. One terminal of the baffle 113 is fixed on the second terminal plate 115 and the baffle 113 is disposed perpendicular to the second terminal plate 115. The other terminal of the baffle 113 is not connected to the first terminal plate 114 to form a passage outlet 117 between the working fluid recuperating region 110 a and the working fluid condensing region 110 b. After the vapor working fluid Fp flows into the pressure vessel 110 via the inlet 111, the vapor working fluid Fp firstly flows through the working fluid recuperating region 110 a and then flows into the working fluid condensing region 110 b via the passage outlet 117.

Referring to FIG. 1, the recuperating pipe 120, disposed in the pressure vessel 110, passes through the working fluid recuperating region 110 a to heat a liquid working fluid Fq flowing through the recuperating pipe 120. In an embodiment, the recuperating pipe 120, such as a straight pipe, a wavy pipe or a spiral pipe, is fixed on the first terminal plate 114 and the second terminal plate 115 and is connected between the pump 170 and the evaporator 160 (referring to FIG. 2). Therefore, the vapor working fluid Fp transfers the thermal energy to the sub-cooled liquid working fluid Fq in the working fluid recuperating region 110 a whose function is like a recuperator.

Before the liquid working fluid Fq, has been boosted by the pump 170, flows into the evaporator 160, the liquid working fluid Fq flows into the recuperating pipe 120 to absorb the thermal energy and increase the temperature of the liquid working fluid so that the requirement of the heat capacity (or heat transfer area) of the evaporator 160 can be reduced.

Referring to FIG. 1, a plurality of deflectors 140 may be configured in the interior of the pressure vessel 110 and disposed in the working fluid recuperating region 110 a and arranged at intervals to form a channel 116, such as an S-shaped channel or a spiral-shaped channel, via which the vapor working fluid Fp passes through the deflectors 140. In an embodiment, the deflectors 140 are disposed for increasing the heat transfer area between the recuperating pipe 120 and the vapor working fluid Fp in the channel 116 and reducing the velocity of the vapor working fluid Fp such that the vapor working fluid Fp can stay longer in the channel 116 and the efficiency of heat exchange can thus be increased.

The deflectors 140 can be directly disposed outside the recuperating pipe 120 and perpendicular to the recuperating pipe 120 for guiding the vapor working fluid Fp to flow along an outer side of the recuperating pipe 120. In an embodiment, the deflectors 140 comprise a plurality of first deflectors 141 and a plurality of second deflectors 142. The first deflectors 141 and the second deflectors 142 are staggered with each other to form an S-shaped channel. The first deflectors 141 are connected to the baffle 113 and perpendicular to the baffle 113. The first deflectors 141 are not connected to an inner wall of the pressure vessel 110 so that a plurality of first channel openings A can be formed. In addition, the second deflectors 142 are connected to an inner wall of the pressure vessel 110 and perpendicular to the inner wall. The second deflectors 142 are not connected to the baffle 113 so that a plurality of second channel openings B can be formed. The first channel openings A and the second channel openings B are staggered with each other and are located on two opposite sides of the channel to form an S-shaped channel. Therefore, the vapor working fluid Fp can pass through the deflectors 140 via the first channel openings A and the second channel openings B sequentially to transfer the thermal energy to a liquid working fluid Fq inside the recuperating pipe 120.

The disclosed first deflectors 141 and the second deflectors 142, such as semi-closed stoppers, control the flowing direction and the velocity of the vapor working fluid, but the disclosure is not limited thereto. For instance, the deflectors 140, such as perforated plates 140 a or spiral deflectors 140 b as indicated in FIGS. 4A and 4B, can achieve the same effect of controlling the flowing direction and the velocity of the vapor working fluid.

Furthermore, twisted tapes, wire coils, wire brushes or blocks can be added to the interior of the recuperating pipe 120 for ionizing the liquid working fluid and generating secondary flows, such that the liquid working fluid can stay longer in the recuperating pipe 120 and the efficiency of heat exchange can be increased. In another embodiment, particles such as nano metals can be added to the liquid working fluid for improving the efficiency of thermal energy absorption. The design of oscillating the liquid working fluid by using ultra-sound or increasing the turbulent disturbance capability by using a swinging wing can also be used in the heat exchanger 101 of the disclosure to increase the efficiency of heat exchange.

The baffle 113 has a passage outlet 117 located on one side of the channel 116 most farther away from the inlet 111. After releasing partial thermal energy in the channel, the vapor working fluid Fp flows into the working fluid condensing region 110 b via the passage outlet 117. Referring to FIG. 1, the cooling stream pipe 130, disposed in the pressure vessel 110, passes through the working fluid condensing region 110 b to cool the vapor working fluid Fp flowing into the pressure vessel 110. In an embodiment, the cooling stream pipe 130, which can be a straight pipe, a wavy pipe or a spiral pipe, is fixed on the first terminal plate 114 and the second terminal plate 115. Moreover, the vapor working fluid Fp transfers the thermal energy to an external cooling stream C in the working fluid condensing region 110 b whose function is like a condenser.

Before the high temperature vapor working fluid Fp is condensed, the high temperature vapor working fluid Fp releases partial thermal energy to lower the temperature of the vapor working fluid Fp, so that the requirement of the heat capacity (or heat transfer area) of the condenser can be reduced.

In an embodiment, the disclosed deflectors 140 can be used in the working fluid condensing region 110 b to form a channel in the working fluid condensing region 110 b, wherein the channel is similar to of the channel 116 as shown in FIG. 1. The arrangement of deflectors is disclosed above, but the disclosure is not limited thereto. The deflectors can be perforated plates, semi-closed stoppers or spiral deflectors. For instance, the deflectors can be directly disposed outside the cooling stream pipe 130 and perpendicular to the cooling stream pipe 130 for guiding the vapor working fluid Fp to flow along an outer side of the cooling stream pipe 130.

Furthermore, twisted tapes, wire coils, wire brushes or blocks can be added to the interior of the cooling stream pipe 130 for ionizing the cooling stream and generating secondary flows, such that the cooling stream can stay longer in the cooling stream pipe 130 and the efficiency of heat exchange can be increased. In another embodiment, particles such as nano metals can be added to a cooling stream for improving the efficiency of thermal energy absorption. The design of oscillating the cooling stream by using ultra-sound or increasing the turbulent disturbance capability by using a swinging wing can also be used in the heat exchanger 101 of the disclosure to increase the efficiency of heat exchange.

Referring to FIG. 2, a heat cycling system 100 according to an embodiment is shown. The heat cycling system 100 comprises a heat exchanger 101 with recuperating and condensing functions, an evaporator 160, a power generation module 150 and a pump 170. The function of the heat exchanger 101 is equivalent to that of a recuperator and a condenser. The evaporator 160 heats the working fluid F up to a vapor state. The power generation module 150 is connected to an outlet of the evaporator 160 through a first pipe 131, and is connected to an inlet of the pressure vessel 110 through a second pipe 132. Besides, the pump 170 is connected to an outlet of the pressure vessel 110 through a third pipe 133, and is connected to an inlet of the recuperating pipe 120 through a fourth pipe 134 to form a closed cycle with recuperating function. Therefore, the heat cycling system 100 can be realized by a closed heat engine cycling system with heat recycling function.

The working fluid used in the ORC system can be formed by organic compounds (such as refrigerants or hydrocarbons etc.) having low boiling point under an atmospheric pressure, and can be heated by a diversity of middle and low grade heat sources such as industrial waste heat, geothermal, hot springs or solar energy. Therefore, the working fluid, having been evaporated, vaporized and converted into a vapor state from a liquid state inside the evaporator 160, is guided to the power generation module 150 to do work and generate power.

In a super low temperature ORC power generating system, room temperature water (or surface seawater) can be used as a heat source to heat the working fluid which uses liquid gas, liquid nitrogen or liquid oxygen as a cooling stream. Therefore, the working fluid, having been evaporated and vaporized inside the evaporator 160, is guided to the power generation module 150 to do work and generate power.

The disclosed power generator module 150 can be composed of an expander 151 (such as turbine, screw expander, scroll expander) and a power generator 152. Referring to FIG. 2, in an embodiment, the thermal energy and pressure of the working fluid F in a high-temperature vapor state can be converted into a shaft power of the expander 151. Then, the mechanic energy generated from the expansion of the working fluid is inputted to the power generator 152 for generating power. In addition, after the work is done, the working fluid F flows through the heat exchanger 101 with recuperating and condensing functions to release partial thermal energy, and the cooling stream C in the cooling stream pipe 130 absorbs residual thermal energy of the vapor working fluid and condenses as a liquid working fluid. Then, the pump 170 boosts the pressure of the liquid working fluid and pumps the working fluid to the evaporator 160 to be heated by the thermal energy released from the heat source H. Thus, a heat cycling system is formed.

The disposition of the baffle 113, the deflectors 140, the recuperating pipe 120 and the cooling stream pipe 130 of the heat exchanger 101 and the design of the channel are disclosed with reference to FIG. 1 and relevant descriptions. Descriptions of the heat exchanging method used in above embodiments are disclosed below. Referring to FIG. 3, a flowchart of a heat exchanging method according to an embodiment of the disclosure is shown. Firstly, the method begins at step 301, a pressure vessel 110 comprising a recuperating pipe 120, a cooling stream pipe 130 and a baffle 113 is provided. The baffle 113 divides the interior of the pressure vessel 110 into a working fluid recuperating region 110 a and a working fluid condensing region 110 b, the recuperating pipe 120 passes through the working fluid recuperating region 110 a, and the cooling stream pipe 130 passes through the working fluid condensing region 110 b. In step 302, a vapor working fluid Fp is introduced into the pressure vessel 110 to heat a liquid working fluid Fq flowing through the recuperating pipe 120. In step 303, the vapor working fluid Fp is guided to flow into the working fluid condensing region 110 b form the working fluid recuperating region 110 a. In step 304, the vapor working fluid Fp is guided to pass through the working fluid condensing region 110 b to cool the vapor working fluid Fp to a liquid state.

It can be known from the disclosed heat exchanging method that the vapor working fluid Fp transfers the thermal energy to the recuperating pipe 120 in the working fluid recuperating region 110 a and then transfers the thermal energy to an external cooling stream C in the working fluid condensing region 110 b. Since the heat transfer of recuperated working fluid and the heat transfer of condensed working fluid are both performed in the pressure vessel 110 and are divided by a baffle 113, both the required pipe length for exchanging the heat and the installation cost of the heat exchanger 101 are reduced. Besides, since only one pressure vessel 110 is required, the certification cost of pressure vessel 110 can also be reduced.

According to the heat exchanger 101 with recuperating and condensing functions and the heat cycling system and the heat exchanging method disclosed in above embodiments, the functions of recuperator and condenser are integrated in one single heat exchanger 101, not only achieving superior thermal energy utilization and recovery efficiency, but also reducing the requirements of the heat capacity of evaporator 160 and condenser and increasing heat cycling efficiency. Therefore, the disclosure has excellent performance in practical application.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents. 

What is claimed is:
 1. A heat exchanger with recuperating and condensing functions, comprising: a pressure vessel having an inlet, an outlet and a baffle, wherein the baffle, located between the inlet and the outlet, divides an interior of the pressure vessel into a working fluid recuperating region and a working fluid condensing region; a recuperating pipe disposed in the pressure vessel, wherein the recuperating pipe passes through the working fluid recuperating region to heat a liquid working fluid flowing through the recuperating pipe; and a cooling stream pipe disposed in the pressure vessel, wherein the cooling stream pipe passes through the working fluid condensing region to cool a vapor working fluid flowing into the pressure vessel, wherein, the vapor working fluid passes through the working fluid recuperating region and then flows into the working fluid condensing region.
 2. The heat exchanger according to claim 1, wherein a plurality of deflectors, configured in the interior of the pressure vessel, is disposed in the working fluid recuperating region and arranged at intervals to form a channel via which the vapor working fluid passes through the deflectors.
 3. The heat exchanger according to claim 1, wherein the baffle has a passage outlet via which the vapor working fluid flows into the working fluid condensing region.
 4. The heat exchanger according to claim 2, wherein the deflectors comprise a plurality of first deflectors and a plurality of second deflectors staggered with each other to form an S-shaped channel.
 5. The heat exchanger according to claim 2, wherein the deflectors are perforated plates, semi-closed stoppers or spiral deflectors.
 6. The heat exchanger according to claim 1, wherein twisted tapes, wire coils, wire brushes or blocks, which make the liquid working fluid and/or cooling stream generate secondary flows, are disposed in the interior of the recuperating pipe and/or the cooling stream pipe.
 7. A heat cycling system, comprising: a heat exchanger with recuperating and condensing functions, comprising: a pressure vessel having an inlet, an outlet and a baffle, wherein the baffle divides the interior of the pressure vessel into a working fluid recuperating region and a working fluid condensing region; a recuperating pipe disposed in the pressure vessel, wherein the recuperating pipe passes through the working fluid recuperating region to heat a liquid working fluid flowing through the recuperating pipe; and a cooling stream pipe disposed in the pressure vessel, wherein the cooling stream pipe passes through the working fluid condensing region to cool a vapor working fluid flowing into the pressure vessel, wherein, the vapor working fluid passes through the working fluid recuperating region and then flows into the working fluid condensing region; an evaporator connected to an outlet of the recuperating pipe to heat the liquid working fluid up to a vapor state; a power generation module connected to an outlet of the evaporator through a first pipe and connected to the inlet of the pressure vessel through a second pipe; and a pump connected to the outlet of the pressure vessel through a third pipe and connected to an inlet of the recuperating pipe through a fourth pipe.
 8. The heat cycling system according to claim 7, wherein a plurality of deflectors, configured in the interior of the pressure vessel, is disposed in the working fluid recuperating region and arranged at intervals to form a channel via which the vapor working fluid passes through the deflectors.
 9. The heat cycling system according to claim 7, wherein the baffle has a passage outlet via which the vapor working fluid flows into the working fluid condensing region.
 10. The heat cycling system according to claim 8, wherein the deflectors comprise a plurality of first deflectors and a plurality of second deflectors staggered with each other to form an S-shaped channel.
 11. The heat cycling system according to claim 8, wherein the deflectors are perforated plates, semi-closed stoppers or spiral deflectors.
 12. The heat cycling system according to claim 7, wherein twisted tapes, wire coils, wire brushes or blocks, which make the liquid working fluid and/or cooling fluid generate secondary flows, are disposed in the interior of the recuperating pipe and/or the cooling stream pipe.
 13. A heat exchanging method, comprising: providing a pressure vessel having a recuperating pipe, a cooling stream pipe and a baffle, wherein the baffle divides an interior of the pressure vessel into a working fluid recuperating region and a working fluid condensing region, the recuperating pipe passes through the working fluid recuperating region, and the cooling stream pipe passes through the working fluid condensing region; introducing a vapor working fluid into the pressure vessel to heat a liquid working fluid flowing through the recuperating pipe; guiding the vapor working fluid to flow into the working fluid condensing region from the working fluid recuperating region; and guiding the vapor working fluid to pass through the working fluid condensing region to cool the vapor working fluid to a liquid state.
 14. The heat exchanging method according to claim 13, wherein a plurality of deflectors, configured in the interior of the pressure vessel, is disposed in the working fluid recuperating region and arranged at intervals to form a channel via which the vapor working fluid passes through the deflectors.
 15. The heat exchanging method according to claim 14, wherein the baffle has a passage outlet via which the vapor working fluid flows into the working fluid condensing region.
 16. The heat exchanging method according to claim 14, wherein the deflectors comprise a plurality of first deflectors and a plurality of second deflectors staggered with each other to form an S-shaped channel.
 17. The heat exchanging method according to claim 14, wherein the deflectors are perforated plates, semi-closed stoppers or spiral deflectors.
 18. The heat exchanging method according to claim 13, wherein twisted tapes, wire coils, wire brushes or blocks, which make the liquid working fluid and/or cooling fluid generate secondary flows, are disposed in the interior of the recuperating pipe and/or the cooling stream pipe. 